Heat pump water heaters are gaining broader acceptance as a more economic and ecologically-friendly alternative to electric water heaters. Heat pump water heaters include a sealed system for heating water to a set temperature. The sealed system generally includes a condenser configured in a heat exchange relationship with a water storage tank within the water heater appliance and an evaporator.
During operation of the sealed system, water vapor can condense or desublimate on the evaporator and form a frost buildup over time. The frost buildup can negatively affect performance of the sealed system. To remove the frost buildup from the evaporator, heat pump water heater appliances are generally configured for performing a defrost cycle periodically. As an example, certain heat pump water heater appliances include heating elements mounted to the evaporator that are activated during the defrost cycle to melt the frost buildup. As the frost buildup melts, liquid runoff is generated.
Collecting the liquid runoff formed during the defrost cycle and directing the liquid runoff away from the evaporator can be difficult. For example, drain lines and drain pans can clog. In particular, dust, vermin, insects and other debris can clog a drain line out of the drain pan. When the drain line is clogged, the drain line can overflow and negatively affect operation and/or a cosmetic appearance of the heat pump water heater.
Accordingly, a heat pump water heater appliance with features for monitoring a drain pan of the heat pump water heater appliance in order to detect clogging of the drain pan would be useful. In addition, a method for identifying a type of liquid within a drain pan of a heat pump water heater appliance would be useful.